JPS5992524A - Method for liquid phase epitaxial growth - Google Patents

Abstract

PURPOSE:To prevent a growth solution from carrying in another solution by a method wherein the progress of work to rotate a crystal growth device made the horizontal direction as the axis is provided. CONSTITUTION:When growth of a first layer is finished, a rotary shaft 13 is rotated as shown with an arrow mark 14 at the extent of 180 deg. to turn the whole of a growth boat 11 upside down. A growth solution 7a drops to be put in a saucer 15. At this time, a substrate 5 for growth is fixed as not to be dropped. The solution 7a finished with growth on the substrate 5 for growth like this is removed completely, and after then, the rotary shaft 13 is rotated again to return the whole of the growth boat to the original position. Therefore, a change of solution composition according to carrying in another solution of the solution used at growth time, and accordingly abnormal epitaxial growth to be generated according thereto can be kept away completely having favorable reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for liquid phase epitaxial growth, and more particularly to a method for liquid phase epitaxial growth of compound semiconductor crystals.

Conventionally, a horizontal sliding boat is used for liquid phase epitaxial growth of compound semiconductor crystals. FIG. 1 is a cross-sectional view of one example. As shown in Fig. 1, a conventional growth boat has a plurality of solution reservoirs 1 (three in Fig. 1) separated from each other. . Equipped with

Generally, in the liquid phase epitaxial growth method using this growth boat, a growth solution 7 (the entire growth solution is expressed as fnia, and each growth solution is expressed as 'e7a, 7b, and 7c) is held in a solution reservoir 1, The growth substrate 5 is placed in the inner wall 6 of the substrate holding plate 4, and the substrate holding plate 4 is first installed in the positional relationship shown in FIG.

Next, the temperature is maintained at a predetermined temperature, and then the temperature is lowered at a constant cooling rate, and at the predetermined temperature, the substrate holding plate 4 is slid in the direction of the arrow 8, and the growth substrate 5f is moved below the solution reservoir 1a. The surface of the growth substrate 5 is brought into contact with the growth solution 7a.

As a result, an epitaxial layer is formed with a desired thickness depending on the desired temperature drop range or the contact time between the growth substrate 5 and the growth solution 7a. Thereafter, a plurality of epitaxial layers (the first
In the figure, three layers) are formed.

In the conventional method, when the substrate is moved, the growth solution is applied to the growth substrate through the slight gap between the boat 2 and the substrate holding plate 4 shown in FIG. 5 brought above.

Further, the crystal growth rate is faster at the edges of the growth substrate 5, and the crystal grows thicker than the center of the growth substrate 5, which is called edge gloss. If the edge gloss is large, the growth solution is brought onto the growth substrate 5.

If such carry-over occurs and the next growth solution comes into contact with the growth substrate 5, the component ratio in this growth solution will not be the predetermined one, and the lattice constant of the epitaxial growth layer will deviate from that of the growth substrate 5. , problems such as uncontrolled crystal composition occur, and normal epitaxial growth cannot be performed.

As a countermeasure to prevent the above-mentioned items from being brought in, conventional methods have been used, such as improving processing accuracy to eliminate the gap between the boat 2 and the substrate holding plate 4, or aligning the thickness of the growth substrate 5 to a constant value and creating a recess in the substrate holding plate 4. Attempts have been made to achieve a growth method that eliminates the gap between the top surface of the growth substrate 5 and the top surface of the growth substrate 5, or reduces edge gloss. There was a drawback that it did not improve.

The purpose of the present invention is to eliminate the drawbacks of the conventional methods as described above,
An object of the present invention is to provide a liquid phase epitaxial growth method that does not involve bringing in a growth solution.

According to the present invention, a liquid phase epitaxial growth method in which a crystal layer is grown on a growth substrate by sequentially bringing a growth substrate into contact with a plurality of growth solutions includes the step of rotating a crystal growth apparatus about a horizontal axis. A liquid phase epitaxial growth method characterized by the following is obtained.

Although the present invention can be applied to any semiconductor material, an example of crystal growth of a double hetero wafer made of InP/InGaAsP system, which has been attracting attention recently, will be explained in detail with reference to the drawings.

FIG. 2 is a cross-sectional view of a growth boat used in a horizontal sliding liquid phase epitaxial growth method according to an embodiment of the present invention. As shown in FIG. 2, it is equipped with a plurality of (three in FIG. 2) solution reservoirs 1 separated from each other, a passageway 9 extending across which the bows 10 can slide, and a growth chamber. growth substrate 5 and growth solution 1 during crystal growth
Boat 11 equipped with 1 and 6 that can hold
The boat is equipped with a rotating shaft 13° for rotating the entire growth boat by at least 180° about the horizontal direction, and a tray 15 for storing the growth solution that is no longer needed after the growth is completed.

First, install the growth device in the positional relationship shown in Figure 2 5 - do. A growth solution 7 is held in a solution reservoir 1.

Growth solutions 7a, 7b, and 7C are In, P mixed solution, In, Ga, AsP mixed solution, and In, respectively.

It is a P mixed solution. InP at the bottom of the recess 6 of the boat 11
It is installed on a growth substrate 5'.

Next, the temperature is heated and maintained at the set temperature, and then the temperature is lowered at a constant cooling rate, and when the predetermined temperature is reached, the boat 10 is moved in the direction of the arrow 12 and the solution reservoir
Align it with the top of the depression 6. The growth solution 7a falls into the depression 6, contacts the growth surface of the InP growth substrate 5 placed at the bottom of the depression 6, and starts crystal growth.

FIG. 3 is a cross-sectional view showing the positional relationship during epitaxial growth. As a result, a first epitaxial layer is formed with a desired thickness depending on the desired temperature drop range or the contact time between the growth substrate 5 and the growth solution 7a.

At the end of the growth of the first layer of the seashore, the axis of rotation of the seaweed 3 is 13ft18
Rotate about 0 degrees in the direction of arrow 14 to turn the entire growth boat upside down. The growth solution 7a6 falls and is stored in a predetermined receiver in the tray 15. At this time, the growth substrate 5 is stopped so that it does not fall.

In this way, the growth solution 7a on the growth substrate 5 is completely removed, and then the rotation shaft 13V is rotated again to return the entire growth boat to its original position.

Next, move in the direction of the arrow 12 to fully grow the second layer in the same way as the first layer.Then, grow the third layer in the same way.When the growth of the third layer is completed, the growth solution 7
C' (f- Remove from above growth substrate 5. In this example, InP layer, InxGat-xAs
tyPy layer (0<x, y<1).

InP layers were epitaxially grown in sequence.

In the method of this example, by rotating and reversing the growth boat at the end of the growth of each layer, the growth was completed and the next growth solution 7 could be completely removed.

This method differs from the conventional method in that it is possible to eliminate the growth solution 7 from being carried in regardless of the degree of the gap between the growth boats 10 and 11 or the amount of edge gloss, and the thickness t of the growth substrate 5 can be Since there is no need to make any adjustments, it is possible to completely eliminate carry-overs with good reproducibility. This resulted in a high quality epitaxial growth layer and at the same time improved yield.

1? In this example, crystal growth was performed by dropping the growth solution onto the growth surface of the growth substrate and bringing it into contact with it, so that a flat epitaxial growth layer without meniscus lines was obtained.

In this example, liquid phase epitaxial growth of three layers was performed, but even more multilayer epitaxial growth can be performed.

Furthermore, in this example, the growth solution was dropped onto the growth substrate and brought into contact with it to grow the crystal, but as shown in the conventional example in FIG. In the growth method, after the growth of each layer is completed, the whole boat is rotated horizontally, and when the growth is finished, the growth solution is dropped and removed. Needless to say, it has the effect of eliminating

According to the epitaxial growth method of the present invention, it is possible to completely prevent, with good reproducibility, changes in the solution composition due to carry-over of a growth solution into other growth solutions during growth, and the abnormal epitaxial growth that accompanies this.

As a result, a high-quality epitaxial growth layer with few defects can be obtained, and at the same time, the yield bt- can be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of a conventional liquid-phase epitaxial growth boat, FIG. 2 is a cross-sectional view of an example of a companion liquid-phase epitaxial growth boat used in an embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view showing relationships during epitaxial growth using the boat of FIG. 2; In each figure, 1... the entire solution reservoir, 2, 10.11...
・Boat, 3.9... Passageway, 4... Substrate holding plate, 5... Growth substrate, 6...
1, 7... Entire growth solution, 8.12...
...Arrow indicating the direction of movement, 13...Rotary shaft for rotating the boat, 14...Arrow indicating the direction of rotation, 15...The receiver is a plate. . 10-

Claims (2)

[Claims] (1) In a liquid phase epitaxial growth method in which a crystal layer is grown on the growth substrate by sequentially bringing the growth substrate into contact with a plurality of growth solutions, there is a step of rotating the crystal growth apparatus around the horizontal direction. -Characteristic liquid phase epitaxial growth method. (2) When bringing the growth substrate into contact with the growth solution, it includes a step of introducing and bringing the nucleus growth solution into contact with the growth surface of the growth substrate. The liquid phase epitaxial growth method described in Section 1.